1. Field of the Invention
Present invention relates to a composition for forming a hard coating layer having excellent anti-fouling property and a hard coating film prepared therefrom.
2. Related Art
Generally, a composition for forming a hard coating layer is used to protect the surface of a material having poor scratch resistance and abrasion resistance in order to maintain the appearance.
The composition for forming a hard coating layer can be applied to glass material such as an automobile windshield, a side mirror, a construction glass, and the like.
To improve scratch resistance and abrasion resistance, various attempts have been made to form a silica film as a hard coating layer on a substrate through plasma enhanced chemical vapor deposition (PECVD), CVD, sputtering, a sol-gel process, and the like. However, when PECVD, CVD or sputtering is used, there is a problem in that an apparatus for PECVD, CVD or sputtering is high-priced and control for forming a good-quality film is difficult. In addition, the sol-gel process requires a high burning temperature of 500° C. or more and thus is not easily accessible.
Furthermore, anti-fouling properties are required because automotive or building exterior materials can easily be contaminated by dust, exhaust gas, snow or rain.
However, the hard coating composition from prior arts often had no anti-fouling property, and since fluorine compound was added as an additive even if the anti-fouling property was present, the anti-fouling property did not persist as time went by.
As a method for imparting anti-fouling property, a water-repellent treatment method has also been used without adding a fluorine compound.
In the water-repelling treatment method, the surface of a material is coated with water-repellent wax to form a hydrophobic coating, thereby allowing rainwater or washing water to fall from the surface of the material to water droplets.
This method has an advantage that contaminants do not remain on the surface of the material, but are easily removed from the surface, even if the contaminants are contained in the rainwater or washing water.
However, the water-repellent treatment method forming a hydrophobic coating only temporarily imparts hydrophobicity, so that the hydrophobic effect is not maintained sufficiently and the hydrophobic coating is easily removed by rainwater or water for washing.
Therefore, there is a need for a composition for forming a hard coating layer capable of sustaining anti-fouling even after a lapse of time, having excellent scratch resistance and abrasion resistance, and capable of easily forming a hard coating layer.